Throttle valve



y 6, 1929. R. w. CLIFFORD 1.720.665

THROTTLE VALVE Filed Feb. 3, 1928 -FIG. I.-

Patented July 16, 1929.

UNITED STATES ROGER W. CLIFFORD, OF SCHENECTAJJY, NEW YORK.v

THROTTLE VALVE.

Application filed February 3, 1928. Serial No. 251,587.

This invention relates to throttle valves of the single poppet type, aninstance of which is exemplified in Letters Patent of the United StatesNo. 1,338,489, granted and issued to Roger 1V. Clifford and Philip J.Nichols, under date of April 27, 1920, upon which this invention is animprovement. The object of the present invention is to provide simple,inexpensive and readily applicable means whereby the supply of motivefluid controlled by a throttle valve of the type above specified, may bemore perfectly graduated in its opening movement than has heretoforebeen practicable.

The improvement claimed is hereinafter fully set forth.

In ordinary practice, it frequently occurs that in starting a heavytrain, the driving wheels of the locomotive will be slipped, by reasonof the engineer moving the throttle lever so as to effect too sudden anadmission of steam, and in too great a volume, to the cylinders. Instarting lighter trains, sudden SllOCliS on the draft gears areproduced.

These objections are obviated by the present invention, in the practiceof which, in the preliminary stages of the unseating movement of thevalve, its area of delivery opening is, at first, slight, after whichsteam delivery is continued, briefly, without increase of deliveryopening, and thereafter, the area of the delivery opening isprogressively increased to the maximum afforded by the limit of lift ofthe valve.

In the accompanying drawing: Figure 1 is a plan view of a throttle valveappliance, illustrating an embodiment of the invention, the valve beingremoved in the upper half of the Figure; and, Fig. 2, a verticaltransverse section, on the line a a of Fig. 1.

In the practice of the invention, referring dcscriptiv' ely to thespecific embodiment thereof which is herein exemplified, an open topped,and open bottomed hood or casing, 1, is, as in Patent No. 1,338,489aforesaid, located at the top of the stand pipe, 2, through. which steampasses from the boiler to the cylinders of a locomotive or other steamengine, being, in this instance, formed integral with said pipe. Abeveled or conical valve seat, 1 is machined at, or near, the bottom ofthe casing, 1, and vertical guiding ribs, 1, are formed on the innerside of the wall thereof.

A cylindrical throttle valve, 8, of the poppet type, which is bored outtruly on its inner surface, and provided, at its bottom, with a bevelledface, 3, is adapted to be seated on the valve seat, 1-, and thereby tocontrol the passa e of steam through the casing from the boiler to thestand pipe. The throttle valve is raised and lowered, from and to'itsseat, by connections to any suitable known valve operating mechanism,which does not, in and of itself, form part of the present invention,and is not, there fore, herein set forth. The valve operating mechanismis connected to a cross head, 5, which is coupled, by a pin, 5, to lugson the upper end of a valve stem, 6, connected, with the capacity of alimited degree of relative vertical movement, to the throttle valve, 3.The throttle valve is guided, in its movements, from and towards itsseat, by the ribs, 1, on the casing, against which a flange, 3*, formedon the periphery of the throttle valve. closely adjacent to the valveface, 3 and having a cylindrical face, bears. The bore of the portion ofthe casing, 1, which surrounds the flange, 3, is made of slightlygreater diameter than said flange, and a narrow steam delivery space, lis thereby presented between the flange and the casing, during thepreliminary portions of the un seating movement of the throttle valve.

The valve stem, 6, carries a pilot valve, 8, seating in a cover plate,3*, which closes the topof the throttle valve, and is secured removablythereto by bolts, 3, and nuts. A properly packed balancing piston, 7 isfitted, with the capacity of relative vertical movement, in the throttlevalve.

The pilot valve and balancing piston operate similarly to thecorresponding members of the appliance of Patent No. 1,338,- 489, and assaid members do not, in and of themselves, form part of the presentinvention, said operation is not herein set forth.

In the operation of the invention, when unseating movement is firstimparted to the throttle valve, the steam delivery opening exposed bysuch movement is limited to the narrow annular steam delivery space, 1,between the periphery of the flange, 1, and the wall of the casing, 1,and this restricted delivery opening does not begin to be increased, inthe further lift of the valve, until the bottom of the flange, 3*,passes the top of the bore of the casing which surrounded it in itspreceding upward traverse. Thereafter, in the continued unseatingmovement, a progressively increasing opening for steam delivery isuncovered, until the maximum which is aiforded by the limit of lift ofthe throttle valve, is attained. It will be obvious that the limit ofdegree of preliminary steam admission which is resultant on thedescribed construction, and mode of operation, effectually prevents thedetrimental results of the undue suddenness of admission whichfrequently is practiced in the operation of the throttle valves ofpresent practiee.

WVhat is claimed as new and desired to be secured by Letters Patent is:

In, an appliance for controlling the flow of motive fluid, thecombination of a throt seating face and a peripheral flange above.

and adjacent thereto; means for unseating and seating said valve; and anopen topped casing, having a valve seat, a plurality of guiding ribs,projecting inwardly, on which the valve flange is adapted to bear, and abore, of greater diameter than the valve flange, said bore beinginterposed between the valve seat and the guiding ribs, therebypresenting a restricted opening for fluid delivery, in the preliminarystage of the unseating movement of the valve.

ROGER W. CLIFFORD.

